Actual mpg change: 37 bfg

The BFG 37s are ~ 6% larger than stock so if you are going an indicated 450 miles on 30 gallons for a reported 15 mpg you would actually have gone 477 miles on 30 gallons for an actual 15.9 mpg.

So if you're quoting MPG without having corrected your speedo...

Truckzor said:

The BFG 37s are ~ 6% larger than stock so if you are going an indicated 450 miles on 30 gallons for a reported 15 mpg you would actually have gone 477 miles on 30 gallons for an actual 15.9 mpg.

So if you're quoting MPG without having corrected your speedo...

Click to expand...

sweet, thank you! not as bad as I thought

Truckzor said:

The BFG 37s are ~ 6% larger than stock so if you are going an indicated 450 miles on 30 gallons for a reported 15 mpg you would actually have gone 477 miles on 30 gallons for an actual 15.9 mpg.

So if you're quoting MPG without having corrected your speedo...

Click to expand...

Very good point here....

I accounted for the discrepancy in my calculations. Still got 1-2 MPG worse with heavier wheels and 37" tires.

I’m thinking 1-2 less would be lucky.

Gsteve said:

I’m thinking 1-2 less would be lucky.

Click to expand...

37" BFGs aren't that that much heavier than stock. There's no way, all else equal, anyone is losing much mpg over stock with them.

Most (all) of these guys reporting reduced MPG failed to adjust their speedo or account for that difference in their "analysis".

Truckzor said:

37" BFGs aren't that that much heavier than stock. There's no way, all else equal, anyone is losing much mpg over stock with them.

Most (all) of these guys reporting reduced MPG failed to adjust their speedo or account for that difference in their "analysis".

Click to expand...

I calculated mine correctly. Here are my results for 87 octane for both:

Stock: 34.4" tire height, 95.2 lbs wheel and tire (measured on a scale)
sample A MPG readout on dash: 16.5mpg
sample A actual miles traveled: 372.0 miles
sample A actual gallons at fill up: 24.393 gallons
sample A actual MPG: 15.25mpg

Aftermarket Nitto Ridge Grappler 37"x12.5" on 20"x9" fuel vapor wheels: 127.2 lbs wheel and tire (measured on same scale as stock on the same day)
Sample B MPG readout on dash: 13.2mpg (this would probably have been 14.2 had I changed my speedo)
sample B miles traveled per uncorrected speedo: 396.4 miles (actual miles traveled was 426.36)
sample B actual gallons at fill up: 31.235 gallons
sample B actual MPG: 13.65mpg

Actual difference of 1.6 mpg on that particular comparison which was as close as I could find in the samples I took for my own comparison.

And as you can see, the mpg reported on the dash is a ballpark estimate at best. To get a true MPG you need to calculate yourself.

Go ahead, poke a hole in my "analysis". I'll wait.

Topic of thread: "Actual mpg change: 37 bfg"

Truckzor said:

37" BFGs aren't that that much heavier than stock.

Click to expand...

ChevyChad said:

Go ahead, poke a hole in my "analysis". I'll wait.

Click to expand...

I found the hole.

ChevyChad said:

Aftermarket Nitto Ridge Grappler 37"x12.5" on 20"x9" fuel vapor wheels: 127.2 lbs wheel and tire (measured on same scale as stock on the same day)

Click to expand...

Come on man.

Truckzor said:

Topic of thread: "Actual mpg change: 37 bfg"

I found the hole.

Come on man.

Click to expand...

I was replying to your following comment:

Truckzor said:

Most (all) of these guys reporting reduced MPG failed to adjust their speedo or account for that difference in their "analysis".

Click to expand...

ChevyChad said:

I was replying to your following comment:

Click to expand...

I guess you missed the part about the 37" BFGs?

Truckzor said:

37" BFGs aren't that that much heavier than stock. There's no way, all else equal, anyone is losing much mpg over stock with them.

Most (all) of these guys reporting reduced MPG failed to adjust their speedo or account for that difference in their "analysis".

Click to expand...

I repeat. Come on man.